2 * JNI interface to C RngStream code
4 * Copyright 2006,2007,2010,2012 The SimGrid Team.
7 * This program is free software; you can redistribute
8 * it and/or modify it under the terms of the license
9 * (GNU LGPL) which comes with this package.
11 package org.simgrid.msg;
13 * Export of RngStreams for Java
15 public class RngStream {
17 * Represents the bind between the RngStream java object and the C object.
21 * Creates and returns a new stream without identifier.
22 * This procedure reserves space to keep the information relative to
23 * the RngStream, initializes its seed Ig , sets Bg and Cg equal to Ig , sets its antithetic and
24 * precision switches to 0. The seed Ig is equal to the initial seed of the package given by
25 * setPackageSeed if this is the first stream created, otherwise it is Z steps ahead
26 * of that of the most recently created stream.
32 * Creates and returns a new stream with identifier "name".
33 * This procedure reserves space to keep the information relative to
34 * the RngStream, initializes its seed Ig , sets Bg and Cg equal to Ig , sets its antithetic and
35 * precision switches to 0. The seed Ig is equal to the initial seed of the package given by
36 * setPackageSeed if this is the first stream created, otherwise it is Z steps ahead
37 * of that of the most recently created stream.
39 public RngStream(String name) {
43 * The natively implemented method to create a C RngStream object.
45 private native void create(String name);
49 protected void finalize() {
53 * Release the C RngStream object
55 private native void destroy();
58 * Sets the initial seed of the package RngStreams to the six integers in the vector seed. This will
59 * be the seed (initial state) of the first stream. If this procedure is not called, the default initial
60 * seed is (12345, 12345, 12345, 12345, 12345, 12345). If it is called, the first 3 values of the seed
61 * must all be less than m1 = 4294967087, and not all 0; and the last 3 values must all be less
62 * than m2 = 4294944443, and not all 0. Returns false for invalid seeds, and true otherwise.
64 public static native boolean setPackageSeed(int seed[]);
66 * Reinitializes the stream g to its initial state: Cg and Bg are set to Ig .
68 public native void resetStart();
70 * Reinitializes the stream g to the beginning of its current substream: Cg is set to Bg .
72 public native void restartStartSubstream();
74 * Reinitializes the stream g to the beginning of its next substream: Ng is computed, and Cg and
77 public native void resetNextSubstream();
79 * If a = true the stream g will start generating antithetic variates, i.e., 1 - U instead of U , until
80 * this method is called again with a = false.
82 public native void setAntithetic(boolean a);
84 * Sets the initial seed Ig of stream g to the vector seed. This vector must satisfy the same
85 * conditions as in setPackageSeed. The stream is then reset to this initial seed. The
86 * states and seeds of the other streams are not modified. As a result, after calling this procedure,
87 * the initial seeds of the streams are no longer spaced Z values apart. We discourage the use of
88 * this procedure. Returns false for invalid seeds, and true otherwise.
90 public native boolean setSeed(int seed[]);
92 * Advances the state of the stream by k values, without modifying the states of other streams (as
93 * in RngStream_SetSeed), nor the values of Bg and Ig associated with this stream. If e > 0, then
94 * k = 2e + c; if e < 0, then k = -2-e + c; and if e = 0, then k = c. Note: c is allowed to take
95 * negative values. We discourage the use of this procedure.
97 public native void advanceState(int e, int g);
100 * Returns a (pseudo)random number from the uniform distribution over the interval (0, 1), after advancing the state by one step. The returned number has 32 bits of precision
101 * in the sense that it is always a multiple of 1/(232 - 208), unless RngStream_IncreasedPrecis
102 * has been called for this stream.
104 public native double randU01();
106 * Returns a (pseudo)random number from the discrete uniform distribution over the integers
107 * {i, i + 1, . . . , j}
109 public native int randInt(int i, int j);
112 * Class initializer, to initialize various JNI stuff
114 public static native void nativeInit();